The Role of the Sunnah
When scholars debate over a certain Islamic topic, they use quotes from the Koran and Sunnah to support their arguments. If a supporting statement they want is not available in the Koran, they quote a Hadith. The Hadith are integral for the survival of Islam. There are a few thousand of them that are available to answer common questions and interpret many verses in the Koran. They address specific Islamic situations or problems and propose solutions.
Traditions of the Prophet
The Koran asks people to observe, learn, and follow the traditions of Prophet Muhammad. Such traditions include how he prayed, ate, slept, walked, spoke, worshipped, and generally went about his life. Muslims learn about these traditions from the Hadith, which give the Prophet's quotes and anecdotes as well as eyewitness accounts by his companions.
Because the Koran urges the true believer to live as the Prophet lived, many Muslims try to emulate him as much as possible. The Koran says that Prophet Muhammad is guided onto the right path, so Muslims believe it is in their best interest to follow the Prophet. Adding extra prayers between the main prayers is an example of a tradition learned from Muhammad and replicated by millions of Muslims.
The Sunnah refers to the entire package of traditions, anecdotes, quotes, and Hadith left by Prophet Muhammad. A Hadith is part of the Sunnah, but specifically a quote from the Prophet.
A Hadith is almost always a quote of Prophet Muhammad from someone who was present with the Prophet at the moment he said it. Usually, a Hadith is preceded by the name of the person who transmitted the information, such as, “According to Aisha, Prophet Muhammad said so and so.” There are thousands of Hadith that are referenced this way.
The Hadith is the word of Muhammad, not Allah. The Hadith were not preserved as well as the Koran, and scholars say that a few Hadith underwent slight distortion as they were transmitted from reference to reference. Therefore, Hadith have three classifications: authenticated Hadith, valid Hadith, and weak Hadith. An authenticated Hadith is a real and accurate quote of Muhammad. A valid Hadith is less established and its integrity suffers from a minor degree of doubt. A weak Hadith is just what the name implies—the Prophet may or may not have said it.
The Qudsi Hadith
A Qudsi Hadith, also known as Hadith Qudsi (holy), is very different from the ordinary Hadith. A Qudsi Hadith is Allah's words narrated through the Prophet; for example, Prophet Muhammad said, “On Judgment Day, Allah will speak to the people of heaven, telling them …” A Qudsi Hadith quotes Allah Himself, but in a manner and style different from the Koran.
There are, however, some scholars who doubt that such a Hadith is entirely the word of Allah. Qudsi Hadith can be used for reference, but they are not considered equal to the Koran. For one thing, a Muslim cannot recite a Qudsi Hadith in prayer, even though it is the word of Allah. The Koran does not mention the Hadith, but Muslims are delighted to have them as an additional source of information about their faith. In the years following the Prophet's death, scholars collected both Qudsi and normal Hadith and preserved them in books that are still in print to this day. Examples of these books are Sahih Al Bukhari and Sahih Muslim, among many others, all readily available in Islamic book sections.
When Muslims say or hear Prophet Muhammad's name, they always follow it with (in Arabic) “Peace and blessings be upon him.” When the name of one of his close friends is mentioned, they follow it with “May Allah be pleased with him.” Muslims also follow the name of Allah with “the Supreme, the Almighty.”